I try to update my exchange 2007 to exchange 2010. I use Microsoft Upgrade from Exchange 2007 - Deployment Checklist link as reference. I do 9 of 17 task and stopped on installation of mailbox role. I received this message: Unable to initialize the Microsoft Exchange Information Store service. Failed to find the working directory parameter from the registry - Error 0x80004005. Also I can't to start this service manually.

Rajnish and Kathy have interisting suggestion that fix the issue, First take backup from your registry, then: 1. Open Registry Editor. 2. In Registry Editor, navigate to the following registry key: HKEY_LOCAL_MACHINE \SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem 3. Create the following value (REG_SZ): Working Directory and give it a value that points to the new database folder. please review: http://sharepoint.mindsharpblogs.com/Kathy/archive/2009/10/16/Uninstalling-Exchange-2007-and-Installing-Exchange-2010-Windows-Server-2008-R2.aspx http://social.technet.microsoft.com/Forums/en/exchangesvradmin/thread/d166370c-01e6-4848-a3dd-5b10f95e9fd7Ibrahim Al Masry http://www.ibra.me/